The first PDA, de Organizer, was reweased in 1984 by Psion, fowwowed by Psion's Series 3, in 1991. The watter began to resembwe de more famiwiar PDA stywe, incwuding a fuww keyboard.[4][5] The term PDA was first used on January 7, 1992 by Appwe ComputerCEOJohn Scuwwey at de Consumer Ewectronics Show in Las Vegas, Nevada, referring to de Appwe Newton.[6] In 1994, IBM introduced de first PDA wif fuww mobiwe phone functionawity, de IBM Simon, which can awso be considered de first smartphone. Then in 1996, Nokia introduced a PDA wif fuww mobiwe phone functionawity, de 9000 Communicator, which became de worwd's best-sewwing PDA. The Communicator spawned a new category of PDAs: de "PDA phone", now cawwed "smartphone". Anoder earwy entrant in dis market was Pawm, wif a wine of PDA products which began in March 1996. The terms "personaw digitaw assistant" and "PDA" appwy to smartphones but are not used in marketing, media, or generaw conversation to refer to devices such as de BwackBerry, iPad, iPhone or Android devices.

A typicaw PDA has a touchscreen for entering data, a memory card swot for data storage, and IrDA, Bwuetoof and/or Wi-Fi. However, some PDAs may not have a touchscreen, using softkeys, a directionaw pad, and a numeric keypad or a dumb keyboard for input; dis is typicawwy seen on tewephones dat are awso PDAs.To have de functions expected of a PDA, a device's software typicawwy incwudes an appointment cawendar, a to-do wist, an address book for contacts, a cawcuwator, and some sort of memo (or "note") program. PDAs wif wirewess data connections awso typicawwy incwude an emaiw cwient and a Web browser.

Many of de originaw PDAs, such as de Appwe Newton and Pawm Piwot, featured a touchscreen for user interaction, having onwy a few buttons—usuawwy reserved for shortcuts to often-used programs. Some touchscreen PDAs, incwuding Windows Mobiwe devices, had a detachabwe stywus to faciwitate making sewections. The user interacts wif de device by tapping de screen to sewect buttons or issue commands, or by dragging a finger (or de stywus) on de screen to make sewections or scroww.

Typicaw medods of entering text on touchscreen PDAs incwude:

A virtuaw keyboard, where a keyboard is shown on de touchscreen, uh-hah-hah-hah. Text is entered by tapping de on-screen keyboard wif a finger or stywus.

Handwriting recognition, where wetters or words are written on de touchscreen, often wif a stywus, and de PDA converts de input to text. Recognition and computation of handwritten horizontaw and verticaw formuwas, such as "1 + 2 =", may awso be a feature.

Stroke recognition awwows de user to make a predefined set of strokes on de touchscreen, sometimes in a speciaw input area, representing de various characters to be input. The strokes are often simpwified character shapes, making dem easier for de device to recognize. One widewy known stroke recognition system is Pawm's Graffiti.

Despite research and devewopment projects, end-users experience mixed resuwts wif handwriting recognition systems. Some find it frustrating and inaccurate, whiwe oders are satisfied wif de qwawity of de recognition, uh-hah-hah-hah.[7]

Touchscreen PDAs intended for business use, such as de BwackBerry and Pawm Treo, usuawwy awso offer fuww keyboards and scroww wheews or dumbwheews to faciwitate data entry and navigation, uh-hah-hah-hah. Many touchscreen PDAs support some form of externaw keyboard as weww. Speciawized fowding keyboards, which offer a fuww-sized keyboard but cowwapse into a compact size for transport, are avaiwabwe for many modews. Externaw keyboards may attach to de PDA directwy, using a cabwe, or may use wirewess technowogy such as infrared or Bwuetoof to connect to de PDA. Newer PDAs, such as de HTC HD2, Appwe iPhone, Appwe iPod Touch, and Pawm Pre, Pawm Pre Pwus, Pawm Pixi, Pawm Pixi Pwus, Googwe Android (operating system) incwude more advanced forms of touchscreen dat can register muwtipwe touches simuwtaneouswy. These "muwti-touch" dispways awwow for more sophisticated interfaces using various gestures entered wif one or more fingers.

Awdough many earwy PDAs did not have memory card swots, now most have eider some form of Secure Digitaw (SD) swot, a CompactFwash swot or a combination of de two. Awdough designed for memory, Secure Digitaw Input/Output (SDIO) and CompactFwash cards are avaiwabwe dat provide accessories wike Wi-Fi or digitaw cameras, if de device can support dem. Some PDAs awso have a USB port, mainwy for USB fwash drives.[dubious– discuss] Some PDAs use microSD cards, which are ewectronicawwy compatibwe wif SD cards, but have a much smawwer physicaw size.

Whiwe earwy PDAs connected to a user's personaw computer via seriaw ports or anoder proprietary connection,[specify] many today connect via a USB cabwe. Owder PDAs were unabwe to connect to each oder via USB, as deir impwementations of USB didn't support acting as de "host". Some earwy PDAs were abwe to connect to de Internet indirectwy by means of an externaw modem connected via de PDA's seriaw port or "sync" connector,[8] or directwy by using an expansion card dat provided an Edernet port.

Most modern PDAs have Bwuetoof, a popuwar wirewess protocow for mobiwe devices. Bwuetoof can be used to connect keyboards, headsets, GPS receivers, and oder nearby accessories. It's awso possibwe to transfer fiwes between PDAs dat have Bwuetoof. Many modern PDAs have Wi-Fi wirewess network connectivity and can connect to Wi-Fi hotspots.[9] Aww smartphones, and some oder modern PDAs, can connect to Wirewess Wide Area Networks, such as dose provided by cewwuwar tewecommunications companies. Owder PDAs from de 1990s to 2006 typicawwy had an IrDA (infrared) port awwowing short-range, wine-of-sight wirewess communication, uh-hah-hah-hah. Few current modews use dis technowogy, as it has been suppwanted by Bwuetoof and Wi-Fi. IrDA awwows communication between two PDAs, or between a PDA and any device wif an IrDA port or adapter. Some printers have IrDA receivers,[10] awwowing IrDA-eqwipped PDAs to print to dem, if de PDA's operating system supports it. Universaw PDA keyboards designed for dese owder PDAs use infrared technowogy.[citation needed] Infrared technowogy is wow-cost and has de advantage of being awwowed aboard.

Most PDAs can synchronize deir data wif appwications on a user's computer. This awwows de user to update contact, scheduwe, or oder information on deir computer, using software such as Microsoft Outwook or ACT!, and have dat same data transferred to PDA—or transfer updated information from de PDA back to de computer. This ewiminates de need for de user to update deir data in two pwaces. Synchronization awso prevents de woss of information stored on de device if it is wost, stowen, or destroyed. When de PDA is repaired or repwaced, it can be "re-synced" wif de computer, restoring de user's data. Some users find dat data input is qwicker on deir computer dan on deir PDA, since text input via a touchscreen or smaww-scawe keyboard is swower dan a fuww-size keyboard. Transferring data to a PDA via de computer is derefore a wot qwicker dan having to manuawwy input aww data on de handhewd device.[citation needed]

Most PDAs come wif de abiwity to synchronize to a computer. This is done drough synchronization software provided wif de handhewd, or sometime wif de computer's operating system. Exampwes of synchronization software incwude:

These programs awwow de PDA to be synchronized wif a personaw information manager, which may be part of de computer's operating system, provided wif de PDA, or sowd separatewy by a dird party. For exampwe, de RIM BwackBerry comes wif RIM's Desktop Manager program, which can synchronize to bof Microsoft Outwook and ACT!. Oder PDAs come onwy wif deir own proprietary software. For exampwe, some earwy Pawm OS PDAs came onwy wif Pawm Desktop, whiwe water Pawm PDAs—such as de Treo 650—have de abiwity to sync to Pawm Desktop or Microsoft Outwook. Microsoft's ActiveSync and Windows Mobiwe Device Center onwy synchronize wif Microsoft Outwook or a Microsoft Exchange server.[citation needed] Third-party synchronization software is awso avaiwabwe for some PDAs from companies wike CommonTime[11] and CompanionLink.[12] Third-party software can be used to synchronize PDAs to oder personaw information managers dat are not supported by de PDA manufacturers (for exampwe, GowdMine and IBM Lotus Notes).

Many companies have devewoped PDA products aimed at de medicaw profession's, such as PDAs woaded wif drug databases, treatment information, and medicaw information, uh-hah-hah-hah. Services such as AvantGo transwate medicaw journaws into PDA-readabwe formats. WardWatch organizes medicaw records, providing reminders of information such as de treatment regimens of patients to doctors making ward rounds. Pendragon and Syware provide toows for conducting research wif, awwowing de user to enter data into a centrawized database using deir PDA. Microsoft Visuaw Studio and Sun Java awso provide programming toows for devewoping survey instruments on de handhewd. These devewopment toows awwow for integration wif SQL databases dat are stored on de handhewd and can be synchronized wif a desktop- or server-based database. PDAs have been used by doctors to aid diagnosis and drug sewection and some studies[who?] have concwuded dat when patients can use PDAs to record deir symptoms, dey communicate more effectivewy wif hospitaw staff during fowwow-up visits. The devewopment of Sensor Web technowogy may wead to wearabwe bodiwy sensors to monitor ongoing conditions, wike diabetes or epiwepsy, which wouwd awert patients and doctors when treatment is reqwired using wirewess communication and PDAs.

PDAs and handhewd devices are awwowed in many cwassrooms for digitaw note-taking. Students can speww-check, modify, and amend deir cwass notes on a PDA. Some educators[who?] distribute course materiaw drough de Internet or infrared fiwe-sharing functions of de PDA. Textbook pubwishers have begun to rewease e-books, which can be upwoaded directwy to a PDA, reducing de number of textbooks students must carry.[19] Brighton and SUSSEX Medicaw Schoow in de UK was de first medicaw schoow to provide wide scawe use of PDAs to its undergraduate students. The wearning opportunities provided by having PDAs compwete wif a suite of key medicaw texts was studied wif resuwts showing dat wearning occurred in context wif timewy access to key facts and drough consowidation of knowwedge via repetition, uh-hah-hah-hah. The PDA was an important addition to de wearning ecowogy rader dan a repwacement.[20] Software companies have devewoped PDA programs to meet de instructionaw needs of educationaw institutions, such as dictionaries, desauri, word processing software, encycwopedias, webinar and digitaw wesson pwanners.

PDAs may be used by music endusiasts to pway a variety of music fiwe formats. Many PDAs incwude de functionawity of an MP3 pwayer. Road rawwy endusiasts can use PDAs to cawcuwate distance, speed, and time. This information may be used for navigation, or de PDA's GPS functions can be used for navigation, uh-hah-hah-hah. Underwater divers can use PDAs to pwan breading gas mixtures and decompression scheduwes using software such as "V-Pwanner".